I have recently bought the above rifle with a 20" barrel and would like to know if anyone knows how to date them. I can not seem to find any serial numbers on the net.This one does not have a tang safety if that helps.I also could not find any reference to the 20" barrel all i can find is the 24" octagon and half octagon barrels. Please excuse me if the barrel configurations before are wrong,I have looked at a lot of things lately and they may have run together Thank You JHW